Mutation vs registry

1. Is mutation mandatory after registry of land? if it is not done, will the sub registrar not chande title of land in his records?

The sub registrar has got no business to change the name of the title holder for any reason whatsoever except following the proper registration duties.

2. If its not done, does it mean title of land is not transfered from seller to buyer (in spite of registered sale deed)No, it is not so, but mutation of records is always better to show possession.

3. What if someone does a mutation of land in his name illegally- will he be the new title holder of land- irrespective of him/ her having a registered sale deed in his name

By merely transferring the name in mutation records, one cannot say that he has title to the property without sale deed registered on his name, it is invalid and illegal.

4. Is there anything else to be done to secure title of land after registered sale deed and mutation

after registration and mutation of records, it is better to take physical possession of land by fencing it all along its boundaries.

5. Is mutation required for all lands (agricultural, muncipal, non muncipal etc.)- also what is difference between muncipal and non muncipal land!!

Mutation is a process of possessing the land in one's name in the  revenue records, hence it is would a requirement to secure the property safely.

6. Is mutation requried for all immovable properties like houses, flats etc. as well or they are required only for land?

Same as above

7. Is there any book availabe in the market which a layman like me can read and understand regarding immovable property laws in India accross states?

Visit a local book stall or any library near your vicinity.

--There are two types of mutations. One is the mutation of Agricultural lands and another one is for non agricultural lands viz. Falts, villas, independent houses, plots, godowns etc. 

For the first one mutation is must and without mutation title will not pass.  Mutation should be entered in the revenue records. 

For the second one, failure to mutate does not take away your right in the sale deed.  That is even though the mutation has not done, the purchaser title will not be effected.  He will remain the owner of the property.  But the only problem of not mutating is you will not get electricity connection, water connection and you cannot pay municipal tax.